1. Field of the Invention
The invention concerns a multiple phase electric machine with a turn-to-turn winding as well as a process for the production of such machines.
2. Description of the Prior Art
Good space utilization in the winding overhangs due to short connection paths and large conductor cross sections create favorable conditions for an increase in power density and efficiency.
Although it is possible to achieve high groove space factors by means of turn-to-turn windings consisting of conductor layers of rectangular cross section which are stacked in direction of the groove depth, their production remains a problem.
In the three-layer winding described in DE-AS 1,005,611 all three layers are bent at different angles towards the shaft.
From DE-AS 1,025,058 a single-layer rotor winding with groove bars is known in which the intersection problem is solved by bending the groove bar only on one side by the full height of the layer towards the shaft and always designing adjacent groove bar ends differently.
U.S. Pat. No. 3,634,708 shows an air-core winding which consists of a conductor layer. In the active portion, the thickness of the armature corresponds to a single conductor thickness. Alternate conductors, as they extend into the crossover portion, occupy two contiguous planes, one of which is a continuation of the single wire thickness plane of the active portion of the winding.
U.S. Pat. No. 4,187,441 relates to brushless electric machines with a multiple disk, pancake, rotor, and stator structure. Elimination of excess stator yoke material would therefore contribute to the realization of increased power density in an electric machine. The stator winding is without special features.
U.S. Pat. No. 5,744,896 shows a brushless electromotive device with a flat coil structure operating with an axially oriented magnetic field. Several flat stator coils lie adjacent to one another and overlap each other. The thickness of the coil and magnetic flux gap is minimized by forming the radially extending side portions of a wire-wound coil in axial direction. Each coil is substantially of the same trapezoidal shape, but the radially extending side portions are coplanar in a different manner.
Furthermore, turn-to-turn windings made of prefabricated conductor parts that are free of bending radii are known. For instance, in DE 41 25 044 C2 multi-phase conductor layers are described in which the conductor cross section in the winding overhangs varies. The number of different conductor designs corresponds to the number of phases resulting in uniform distribution of current density in the winding overhang space.
In DE 42 34 145 C1 turn-to-turn windings are described whose conductor lanes of different phases yield to each other in the winding overhang in direction of the groove depth and thereby utilize the space in front of the yoke. The length of the conductor is therefore dependent on the groove depth and conductor lanes of different phases are of different designs.
From DE 43 21 236 C1 a turn-to-turn winding is known that is characterized by intertwined conductor lanes. Conductor lanes of a double layer can not be produced independently of each other. The conductor layers consist of many individual parts that have to be positioned into their final location prior to joining them.
The objective of the present invention is to advance a multiple phase electric machine with overlapping conductor lanes in such a manner that short connection paths and complete and uniform space utilization in the winding overhangs is achieved at the lowest possible production cost.